If you use the Relocator to transfer Entei, Suicune, or Raikou to your game, then you can catch Zoroark. First, you must get to Nimbasa City in the game. Once there, head northeast to Route 16, and check the northern part of that area to find the entrance to Lostlorn Forest.
In the northeast part of the forest, you will find a camper parked there. If you bring the shiny Entei, Suicune or Raikou with you that you transferred with the Relocator, then a woman will dash out of the RV and growl at you, and then a pokémon battle will begin.
If you bring Entei, then the pokémon will appear to be Suicune. If you bring Raikou, it will appear to be Entei. If you bring Suicune, it will appear to be Raikou. However, once you hit the pokémon once, it will transform into Zoroark, revealing that the other one was just an illusion.